Background

I had run two oracles, one is old oracle and the other oracle is the new oracle.
When an event occurs, both oracles subscribe at the same time.
And at the same time execute the transaction.
Two transactions are received in blockChain at the same time.
Resultly, One transaction is success, another transaction is failed.
The failed reason is account sequence mismatched.

Implement

When oracle starts, it gets the active uniqueID from the blockchain and compares one's own uniqueID.

• If two uniqueID match, Oracle starts subscribing to the vote event.
• Is not matched, Oracle doesn't subscribe to the vote event.
• In both case, It does subscribed OracleUpgradeEvent.

And when Oracle receives OracleUpgradeEvent, it compares one's own UniqueID.

• If two uniqueID match, Oracle starts subscribing to the vote event.
• Is not matched, Oracle stopping subscribe to the vote event.